Polyamide moulding compound for producing components with a high weld line strength

Abstract

The invention relates to a thermoplastic polyamide moulding compound consisting of the following components: (A) 30 to 74.5 wt.% of at least one partially crystalline, partially aromatic copolyamide 6T / Z with a melting point of at least 270°C, wherein the polyamide unit Z is formed from at least one lactam or an aminocarboxylic acid and / or from polyamide units different from 6T consisting of at least one diamine and at least one dicarboxylic acid, wherein the 6T content in 6T / Z is more than 50 mol-%, based on the molar proportions of all polyamide units; (B) 25 to 50 wt.% glass fibres with an average diameter of 5 to 8 µm, wherein the glass fibres are coated with a sizing composition containing (b1) at least one silane compound, (b2) at least one polymer or copolymer based on unsaturated carboxylic acids and / or unsaturated carboxylic acid anhydrides, and (b3) an epoxy resin, a polyurethane resin, or a polyamide resin, with the proviso that if component (b3) is a system containing carboxylic acid and / or anhydride, the sizing composition may also omit component (b2); (C) 0.5 to 8 wt.% impact modifier; (E) 0 to 20 wt.% amorphous, partially aromatic polyamide; (D) 0 to 10 wt.% additives other than (A)-(C) and (E); and wherein the sum of components (A) to (E) totals 100 wt.% of the polyamide moulding compound.

Description

[0001] TITLE POLYAMIDE MOULDING COMPOUND FOR THE PRODUCTION OF COMPONENTS WITH HIGH

[0002] Weld line strength

[0003] TECHNICAL FIELD

[0004] The present invention relates to polyamide molding compounds for producing components with high weld line strength and components produced using such a polyamide molding compound as well as processes for producing such polyamide molding compounds and processes for producing components from such polyamide molding compounds.

[0005] STATE OF THE ART

[0006] Polyamide-based components, such as fiber-reinforced injection-molded parts, are increasingly being used as components in the automotive industry. There, they are replacing previously used metallic components, among other things, because they not only offer the advantage of their low specific weight, but also because their mechanical and thermal properties can be adapted to the specific loads of the component by incorporating various components.

[0007] Filled plastics are used for such components. The molding compound contains a thermoplastic and a filler. Fillers of any shape, such as elongated or spherical particles, can be used.

[0008] An important example of such filled plastics are fiber-reinforced molding compounds, which contain a thermoplastic and are reinforced with fibers, particularly glass fibers. When such molding compounds are injected into an injection mold in a molten state, the melt flow during cavity filling leads to an orientation of the fillers and / or an uneven distribution of the fillers within the plastic matrix. Among other things, strong shear and extensional flows are responsible for this, which provoke an alignment of the filler particles or demixing. This leads to anisotropic properties of the component with regard to, for example, its strength, stiffness, shrinkage, or even thermal conductivity and expansion. Anisotropic shrinkage, in turn, is a major cause of component warpage, which is frequently found in fiber-reinforced injection-molded parts.A particularly pronounced anisotropy occurs in the flow shadow of flow obstacles. Weld lines, which are unavoidable in many injection molding processes, also develop fiber orientations parallel to the weld line, so that when subjected to stress perpendicular to the weld line, these areas exhibit strengths only comparable to those of the unreinforced or unfilled matrix material.

[0009] A fundamental distinction is made between static and dynamic weld lines. Static weld lines occur, for example, during the welding process when joining thermoplastic molded parts. A dynamic weld line is created in a plastic component during the injection molding process by the confluence of at least two mass flows, e.g., behind cavities, due to differences in wall thickness, or due to multiple gates or injection points on the mold. When two flow fronts meet, a weld line, also called a weld line or flow line, is formed at the point of confluence. These seams appear visually as lines. A weld line is therefore a frequently visible surface effect on injection-molded parts.

[0010] A weld line is a potential weak point in a component. Flow fronts usually collide perpendicularly due to volumetric expansion and weld together. The lower the pressure and temperature, the lower the strength of the weld line. Due to the shear and flow conditions during the injection molding process, reinforcing fibers often orient themselves parallel to the weld line. If the melt has cooled so much that the intersecting melt fronts can no longer completely weld together, the weld line is often visible on the surface as a V-shaped notch. If tensile stresses occur in this area, the notch effect causes excessive stress at the weld line, which then acts as a predetermined breaking point.

[0011] WO-A-2010 / 014801 discloses the production of heat-resistant polyamide moldings in which polyhydric alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, ditrimethylolpropane, D-mannitol, D-sorbitol, or xylitol are admixed with the polyamide. Polyamide blends can also be used. According to the exemplary embodiments, the polyamide blends contain a larger proportion of an at least partially aromatic polyamide and a smaller proportion of an aliphatic polyamide. WO-A-2011 / 94553 describes corresponding polyhydroxy polymers for comparable applications.

[0012] EP-B-2 307 480 relates to heat-resistant thermoplastic articles with co-stabilizers. The articles are made from polyamide compositions containing at least one polyhydric alcohol with more than two hydroxyl groups and a number-average molecular weight (Mn) of less than 2,000, as well as co-stabilizers selected from secondary arylamines and hindered amine light stabilizers (HALS), and mixtures thereof. Reinforcing agents are also included in the polyamide resin.

[0013] WO-A-2015 / 022404 describes a process for producing a thermoplastic molding compound which has improved weld line strength while simultaneously maintaining mechanical strength compared to known, fiber-reinforced thermoplastic molding compounds, comprising the following steps: melting a first granulate containing at least one thermoplastic polymer A1 and at least one fibrous reinforcing material B2 with an average fiber length of 4.5 to 13.0 mm; admixing at least one fibrous reinforcing material B1 with an average fiber length of 0.15 to 4.2 mm or a second granulate containing at least one thermoplastic polymer A2 and at least one fibrous reinforcing material B1 with an average fiber length of 0.15 to 1.2 mm;or melting a mixture comprising a first granulate containing at least one thermoplastic polymer A1 and at least one fibrous reinforcing material B2 having an average fiber length of 4.5 to 13.0 mm and a second granulate containing at least one thermoplastic polymer A2 and at least one fibrous reinforcing material B1 having an average fiber length of 0.15 to 1.2 mm;

[0014] WO-A-2019 / 149791 describes the use of polyhydric alcohols having more than two hydroxyl groups in polyamide compositions containing at least one polyamide for increasing the weld line strength after heat aging of molded articles produced from the polyamide composition by injection molding, wherein during injection molding at least two flow fronts of the molten polyamide composition meet and form at least one weld line.

[0015] In this context, WO-A-2020 / 173766 describes the use of glass fibers having a tensile strength according to DIN ISO 527-5 of 86.0 to 92.0 GPa, a tensile modulus of elasticity according to DIN ISO 527-5 of 2600 to 3200 MPa, and a softening point according to DIN ISO 7884-1 of 900 to 950 °C, for increasing the weld line strength of molded articles made from molding compounds containing thermoplastic polyamides. EP-A-1728615 describes a process for compensating the orientation of fillers and / or the distribution of fillers in a molding compound made from filled plastic of an injection-molded part. Such a process is particularly required in injection molding and can stabilize the weld line. The process is characterized in that the injection mold and the molding compound are subjected to sound during injection molding in the injection mold. The sound has a frequency in the range of the spectrum of the first ten natural frequencies of the filler-matrix system.Exposure to this sound causes the fillers, such as fibers, to be distributed more isotropically within the injection-molding compound in terms of their orientation and distribution, resulting in significantly improved mechanical and optical properties of the injection-molded part. EP-A-0346825 describes, in this context, a molding compound consisting of a polyamide or a resin mixture of a polyamide resin and a polymer of a monomer with a vinyl group and an inorganic filler consisting of a glass filler and calcium carbonate.

[0016] WO-A-2018 / 060270 describes in this context a polymer composition consisting of (A) a polymer comprising at least (A-1) a first semi-crystalline semi-aromatic polyamide (SSPA) and (A-2) a functionalized polymer; (B) 5-69 wt.% of a reinforcing agent and (C) 0-25 wt.% of one or more other components; wherein the SSPA is present in an amount in the range of 30-90 wt.%; has a melting temperature (Tm) of at least 300°C, and consists of: (A-1-a) 90-100 mol.% of repeating units derived from (i) aromatic dicarboxylic acid and (ii) diamines, and (A-

[0017] 1-b) 0 - 10 mol% of repeating units derived from other monomers; and the diamines (ii) from 80 - 95 mol% linear aliphatic diamine, 5 - 20 mol%

[0018] 2-methylpentamethylenediamine and 0 - 10 mol% of other diamines; wherein the functionalized polymer (A-2) comprises a functionalized semi-crystalline polyolefin in an amount of 1 - 15 wt.%, and wherein the weight percentages (wt.%) of the components

[0019] (A), (B) and (C) as well as of SSPA and the functionalized semi-crystalline polyolefin are based on the total weight of the composition, while the sum of (A),

[0020] (B) and (C) is 100 wt.%.

[0021] EP-A-3330319 describes polyamide molding compositions which have a relative permittivity of not more than 3.5 at 2.45 GHz and contain the following components: (A) 25 to 80 wt.% of a mixture of Aa) 50.1 to 90 wt.% of at least one semi-crystalline, aliphatic polyamide and Ab) 10 to 49.9 wt.% of at least one amorphous or microcrystalline polyamide, wherein the proportions of components Aa) and Ab) add up to 100 wt.% and wherein the mixture of components Aa) and Ab) has on average at least 5.7 C atoms not involved in the amide group per amide group in the mixture (A), (B) 20 to 65 wt.% of at least one glass filler, consisting of glass with an alkali oxide and alkaline earth oxide content of 0 to 12 wt.%, based on the composition of the glass, selected from a group consisting of fibers, ground fibers, particles, flakes, spheres and mixtures thereof and (C) 0 to 10 wt.-% additives, where the sum of components (A), (B) and (C) is 100 wt.%.

[0022] EP-A-3156435 describes copolyamides formed from a diamine component, a dicarboxylic acid component, and optionally a lactam and / or ω-amino acid component. The invention further relates to a polyamide molding compound containing at least one of these copolyamides. Moldings produced from these molding compounds are used in the automotive sector, in the household sector, in measurement, control, and automation technology, or in mechanical engineering. WO-A-2015 / 071281 describes a polyamide molding compound, in particular for producing heat-resistant molded parts, having the following composition: (A) 20 to 79% by weight of at least one partially aromatic polyamide in the form of a copolyamide containing 50 to 80 mol% of units formed from hexanediamine and terephthalic acid; (B) 1 to 15% by weight of at least one impact modifier; (C) 20 to 60% by weight of at least one carbon fiber; (D) 0 to 5 wt.% of at least one additive, wherein components (A) to (D) add up to 100 wt.%.The document demonstrably discloses false information regarding the composition of the sizing on the glass fibers of type Vetrotex 995 EC10-4.5.

[0023] EP-A-2927263 describes a polyamide molding compound, in particular for use for components in the drinking water sector, comprising the following components: (A) 25 - 74.9 wt. % of at least one semi-crystalline, semi-aromatic polyamide 6T / 6I, formed from: (a1) 65 to 82 mol-% terephthalic acid based on the sum of the dicarboxylic acids used; (a2) 18 to 35 mol-% isophthalic acid based on the sum of the dicarboxylic acids used; (a3) ​​1,6-diaminohexane; (a4) at least one monofunctional carboxylic acid; (a5) a phosphorus compound; with the first proviso that the molar ratio of component (a3) ​​to the sum of the dicarboxylic acids used ((a1) + (a2)) is at least 1.04; and with the second proviso that the molar ratio of component (a4) to component (a3) ​​is in the range of 0.01-0.08; (B) 25 - 60 wt.% fibrous reinforcing materials; (C) 0 - 30 wt.% particulate fillers; (D) 0.1 - 2.0 wt.- % heat stabilizers, provided that no copper-containing stabilizers are included; (E) 0 - 2 wt.% carbon black; (F) 0 - 4 wt.% auxiliaries and / or additives other than C, D and E; the sum of components (A)-(E) being 100 wt.%.

[0024] WO-A-2018 / 011131 describes a polyamide molding compound consisting of the following components: (A) 35-68% by weight of at least one semi-crystalline, semi-aromatic, thermoplastic polyamide based on aliphatic diamines having 4-8 carbon atoms and a melting temperature of at least 270°C; (B) 15-22% by weight of carbon fibers; (C) 18-30% by weight of glass fibers; (D) 1-10% by weight of impact modifier different from (E) and / or polymers different from (A), (E) and (F); (E) 0-10% by weight of ethylene-vinyl acetate copolymer; (F) 0-3% by weight of additives. The sum of components (A)-(F) is 100 wt.%, the sum of components (B)-(C) is in the range from 33 to 48 wt.%, and the sum of components (D)-(E) is in the range from 2 to 12 wt.%. The molding compound allows the production of dimensionally stable, electrically conductive components, e.g., for the automotive sector and for contact with fuels, especially gasoline containing methanol.

[0025] PRESENTATION OF THE INVENTION

[0026] It is an object of the present invention to provide a polyamide molding compound which has good mechanical and particularly preferably good thermo-mechanical properties, which can preferably be processed well by injection molding, and in particular has good weld line strength, which is preferably high not only immediately after production but also after exposure to chemicals.

[0027] Preferably, the molded articles produced from the proposed polyamide molding compounds by injection molding have good mechanical properties even after prolonged chemical and / or heat aging at high temperatures.

[0028] The object of the present invention is in particular to provide polyamide compositions which are suitable for the production of injection-molded moldings which exhibit increased weld line strength after heat aging.

[0029] The invention therefore relates in particular to a thermoplastic polyamide molding compound as defined in claim 1.

[0030] Specifically, it is a thermoplastic polyamide molding compound consisting of the following components:

[0031] (A) 37 to 75 wt.% or 30 - 74.5 wt.% of at least one semi-crystalline, semi-aromatic copolyamide 6T / Z having a melting point of at least 270 °C, wherein the polyamide unit Z is composed of at least one lactam or one aminocarboxylic acid and / or of blocks different from 6T composed of at least one diamine and at least one dicarboxylic acid, wherein in 6T / Z the 6T proportion is more than 50 mol%, based on the mol proportions of all polyamide units;

[0032] (B) 25 to 45 wt.% or 25 - 50 wt.% of glass fibers having an average diameter of 5 to 8 pm or 5 to 7 pm, wherein the glass fibers are coated with a sizing composition (b) containing

[0033] (b1) at least one silane compound

[0034] (b2) at least one polymer or copolymer based on unsaturated carboxylic acids and / or unsaturated carboxylic anhydrides, and (b3) at least one epoxy, polyurethane or polyamide resin, with the proviso that if component (b3) is a system containing carboxylic acid and / or anhydride, the sizing composition may also not contain component (b2);

[0035] (C) 0 to 8 wt% or 0.5-8 wt% impact modifier;

[0036] (E) 0 to 20 wt.% amorphous, semi-aromatic polyamide,

[0037] (D) 0 to 10 wt.% of additives other than (A) - (C) and (E); and wherein the sum of components (A) to (E) amounts to 100 wt.% of the polyamide molding composition.

[0038] For the purposes of the present invention, the term "polyamide" (abbreviation PA) is understood as a generic term that includes homopolyamides and copolyamides. The chosen spellings and abbreviations for polyamides and their monomers correspond to those defined in ISO standard 1874-1 (2011, (D)). The abbreviations used therein are used synonymously with the IUPAC names of the monomers below; in particular, the following abbreviations for monomers are used: T for terephthalic acid (CAS No. 100-21-0), I for isophthalic acid (CAS No. 121-95-5), BAC for bis(aminomethyl)cyclohexane, of which 1,3-bis(aminomethyl)cyclohexane (1,3-BAC) and 1,4-bis(aminomethyl)cyclohexane (1,4-BAC) are included. 6T stands for polyamide units composed of 1,6-hexamethylenediamine and terephthalic acid.

[0039] According to a first preferred embodiment, the polyamide molding composition is characterized in that Z of component (A) is composed of polyamide units of at least one lactam or aminocarboxylic acid having at least four, preferably 5-12 carbon atoms, wherein preferably lactam and / or aminocarboxylic acid are selected as aliphatic linear systems, and / or Z is composed of polyamide units other than 6T composed of at least one diamine having 5-12 carbon atoms and at least one dicarboxylic acid having 5-12 carbon atoms, preferably diamines are selected as aliphatic linear or cyclic diamines and further preferably dicarboxylic acids are selected as aliphatic linear dicarboxylic acids.

[0040] The following monomers are suitable as diamines: 1,4-butanediamine, 1,5-pentanediamine, 2-methyl-1,5-pentanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,6-hexanediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 1,8-octanediamine, 2-methyl-1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, m-xylylenediamine and p-xylylenediamine, where 1,6-hexanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane are preferred.

[0041] The following monomers are suitable as dicarboxylic acids: adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, C36 dimer fatty acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, cis- and / or trans-cyclohexane-1,4-dicarboxylic acid and / or cis- and / or trans-cyclohexane-1,3-dicarboxylic acid (CHDA), and mixtures thereof. Adipic acid, isophthalic acid, sebacic acid, and dodecanedioic acid are preferred.

[0042] Furthermore, the polyamides can also contain lactams or aminocarboxylic acids, in particular α,ω-amino acids or lactams with 6 to 12 carbon atoms, the following examples being mentioned: m-aminobenzoic acid, p-aminobenzoic acid, caprolactam (CL), α,ω-aminocaproic acid, α,ω-aminoheptanoic acid, α,ω-aminooctanoic acid, α,ω-aminononanoic acid, α,ω-aminodecanoic acid, α,ω-aminoundecanoic acid (AUA), laurolactam (LL), and α,ω-aminododecanoic acid (ADA). Caprolactam, α,ω-aminocaproic acid, α,ω-aminoundecanoic acid, laurolactam, and α,ω-aminododecanoic acid are particularly preferred.

[0043] The copolyamide 6T / Z can be selected from the group 6T / 61, 6T / DT, 6T / BACT, 6T / 66, 6T / 610, 6T / 612, 6T / 6I / 66, 6T / 6I / 6, 6T / 6I / 610, 6T / 6I / 612 or a mixture thereof, wherein preferably the proportion of polyamide units other than 6T, in particular the 6I, DT, 66, 610, 612 or BACT proportion is more than 20 mol% and wherein the said copolyamides may optionally comprise further polyamide units XY selected from the group consisting of 56, 66, 610, 612, BACI, BAC6, BAC10 and BAC12 in a proportion of less than 30 mol%.

[0044] It is particularly preferred if the copolyamide 6T / Z is selected as 6T / 6I with a proportion of 6T blocks of 60-80 mol%, preferably in the range of 65-75 mol%.

[0045] Preferably, the copolyamide 6T / Z, particularly preferably in the form of 6T / 6I, has a melting point of more than 300 °C, particularly preferably of at least 310 °C, and particularly preferably in the range of 320-330 °C.

[0046] The melting point for the purposes of this application is measured on granules according to ISO 11357-3 (2018), as further specified below.

[0047] The copolyamide 6T / Z additionally or alternatively preferably has a relative viscosity in the range of 1.3-1.8, particularly preferably in the range of 1.5-1.75, most preferably in the range of 1.6-1.7, in each case measured under the conditions and concentrations specified in the experimental description.

[0048] With regard to the proportions within the polyamide molding compound, the following preferably applies: the proportion of component (A) is in the range of 37-74.5% by weight or 42-70% by weight, preferably in the range of 48-64.4% by weight; and / or the proportion of component (B) is in the range of 30-45% by weight, preferably in the range of 35-42% by weight; and / or the proportion of component (C) is in the range of 0-6% by weight, or 0.5-6% by weight or 0.5-5% by weight, preferably in the range of 0.7-5.0% by weight or 0.7-3.5% by weight or preferably in the range of 0.5-5% by weight; and / or the proportion of component (E) is in the range of 5-20% by weight, preferably in the range of 6-16% by weight; and / or the proportion of component (D) is in the range of 0-7 percent by weight, preferably in the range of 0.1-5.0 percent by weight, whereby the sum of components (A)-(E) adds up to 100 percent by weight of the polyamide molding compound.

[0049] The glass fibers of component (B) preferably have a length in the range of 2-7 mm, preferably in the range of 3-5 mm, which is the length of the starting material.

[0050] Preferably, the glass fibers of component (B) have an average diameter (arithmetic mean) in the range of 5-8 pm, preferably in the range of 6-7 pm.

[0051] The glass fibers of component (B) are preferably E-glass fibers (E = Electric) and / or have a round cross-section. E-glass fibers consist of 52 to 62% silica and 12 to 16% alumina according to ASTM D578-00.

[0052] For improved compatibility with the thermoplastic matrix, the glass fibers (B) are provided with a sizing composition (b) containing at least one silane compound (b1), at least one polymer or copolymer based on unsaturated carboxylic acids and / or unsaturated carboxylic anhydrides (b2), and an epoxy, polyurethane, or polyamide resin (b3). The sizing composition (b) is preferably used in amounts of 0.2 to 2.0 wt. %, particularly preferably 0.3 to 1.5 wt. %, and in particular 0.4 to 1.2 wt. %, each stated as dry matter based on component (B) for the surface coating.

[0053] Component (b1): Preferred silane compounds are trialkoxysilanes, dialkoxysilanes, epoxysilanes, vinylsilanes, (meth)acryloxysilanes, aminosilanes and mercaptosilanes.

[0054] Geeignete Vertreter dieser Silanverbindungen sind z.B. y-Glycidoxypropylmethyl- dimethoxysilan, y-Glycidoxypropylmethyldiethoxysilan, Vinylmethyldimethoxysilan, Vinylmethyldiethoxysilan, Y-(Meth)acryloxypropylmethyldimethoxysilan, y- (Meth)acryloxypropylmethyldiethoxysilan, ((Meth)acryloxymethyl)methyldimethoxysilan, y- (Meth)acryloxypropyltrimethoxysilan, Y-(Meth)acryloxypropyltriethoxysilan,

[0055] (Meth)acryloxypropyldimethylmethoxysilan, (Meth)acryloxypropyldimethylethoxysilan, y- Aminopropylmethyldiethoxysilan, N-ß-(Aminoethyl)-Y-aminopropylmethyl-dimethoxysilan, N-ß-(Aminoethyl)-Y-aminopropyl-methyldimethoxysilan, N-ß-(Aminoethyl)-Y- aminoisobutylmethyldimethoxysilan, Y-Aminopropylmethyldi-methoxysilan, N-ß- (Aminoethyl)-Y-aminopropyl-methyldiethoxysilan, 3-Mercaptopropylmethyldimethoxysilan, Y-Aminopropylmethyldiethoxysilan, N-ß-(Aminoethyl)-Y-aminopropylmethyl- dimethoxysilan, N-ß-(Aminoethyl)-Y-amino-propylmethyldimethoxysilan, N-ß-(Aminoethyl)- Y-aminoisobutylmethyldimethoxy-silan, Y-Aminopropylmethyl-dimethoxysilan, N- ß- (Aminoethyl)-Y-aminopropyl-methyldiethoxysilan, Y _ Aminopropyltriethoxysilan, y- Aminopropyl-trimethoxysilan, N-ß-(Aminoethyl)-Y-aminopropyl-trimethoxysilan, N-ß- (Amino-ethyl)-Y-aminopropyl-triethoxysilan, Diethylentriaminopropyltrimethoxysilan, BIS-(Y- trimethoxy-silylpropyl)amin, N-Phenyl-Y-aminopropyltrimethoxysilan, Y _Amino-3,3-dimethylbutyltrimethoxysilane, Y-aminobutyltriethoxysilane, polyazamidesilane.

[0056] Furthermore, suitable silane compounds are those of the general formula (X-(CH2)n)k-Si-(OC m H 2m+ l)4-k, in which the substituents have the following meaning: X: NH2-, HO-, epoxy n: an integer from 2 to 10, preferably 3 to 4, m: an integer from 1 to 5, preferably 1 to 2, k: an integer from 1 to 3, preferably 1.

[0057] Particularly preferred silane compounds are primary and secondary aminosilane compounds, such as aminopropyltrimethoxysilane, aminobutyltrimethoxysilane, aminopropyltriethoxysilane, aminobutyltriethoxysilane, bis(3-triethoxysilylpropyl)amine, and N-[3-(trimethoxysilyl)propyl]ethylenediamine. A particularly preferred silane compound is an aminoalkyltrialkoxysilane, preferably aminopropyltriethoxysilane or aminopropyltrimethoxysilane.

[0058] The silane compound (b1) is preferably contained in the dry sizing composition (b) in an amount between 2 and 20 wt.%, particularly preferably between 3 and 15 wt.%.

[0059] Component (b2):

[0060] The size of the present invention further contains, as component (b2), a homopolymer or copolymer based on unsaturated carboxylic acids or unsaturated carboxylic anhydrides, or their salts. These are preferably polymers and copolymers based on acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, aconitic acid, maleic anhydride, itaconic anhydride, and aconitic anhydride. Particularly preferably, they are (meth)acrylic acid polymers or copolymers, olefin-maleic anhydride copolymers, or mixtures thereof. Component (b2) is preferably present in the dry size composition (b) in an amount of 1 to 70.0 wt. %, particularly preferably 5 to 50 wt. %. The unsaturated carboxylic acid is preferably the (meth)acrylic acid monomer having the formula CH2=CX-COOH, where X can be a hydrogen atom or a methyl or an alkyl group having 1 to 10 carbon atoms.Acrylic acid and methacrylic acid are particularly preferred as unsaturated carboxylic acids. Thus, polyacrylic acid, polymethacrylic acid, or copolymers containing acrylic acid and methacrylic acid are preferred.

[0061] Preferred unsaturated anhydrides are maleic anhydride, itaconic anhydride and aconitic anhydride, with maleic anhydride being particularly preferred.

[0062] Suitable comonomers for the unsaturated carboxylic acids and anhydrides are olefins, especially α-olefins. Preferred comonomers are ethylene, propene, butene, isobutene, butadiene, or pentadiene.

[0063] Preferred copolymers containing acrylic acid or methacrylic acid are ethene-acrylic acid and ethene-methacrylic acid copolymers. Preferred olefin-maleic anhydride copolymers are ethene-maleic anhydride, butadiene-maleic anhydride, but-1-ene-maleic anhydride, isobutylene-maleic anhydride, and (meth)acrylate-maleic anhydride copolymers.

[0064] Furthermore, the salts of these homopolymers or copolymers are also preferred. The salt of polyacrylic acid or acrylic acid copolymers can be an alkali metal or ammonium salt. The degree of neutralization of the polyacrylic acid or acrylic acid copolymers can be between 20% and 90%. Preferred salts are those of ammonium hydroxide, with a degree of neutralization of 30-60%. Generally, the ammonium hydroxide is added to the aqueous solution of polyacrylic acid to achieve a pH of approximately 5 or higher.

[0065] Particularly preferred components (b2) are polyacrylic acid or its alkali metal or ammonium salts, as well as ethene-maleic anhydride copolymers or mixtures thereof. Alternatively, polymers grafted with acrylic acid or maleic anhydride, in particular polyolefins such as polyethylene, polypropylene, polybutene, polyethylene-co-propylene, or polyethylene-co-butylene, can also be used as component (b2).

[0066] Component (b3):

[0067] As a further component, the sizing composition (b) also contains at least one epoxy resin, a polyurethane resin, or a polyamide resin as component (b3). Component (b3) is preferably present in the dry sizing composition (b) in an amount between 5 and 95 wt.%, particularly preferably between 10 and 80 wt.%.

[0068] Preferred epoxy resins are bisphenol A or bisphenol F epoxy resins, epoxy ester resins, epoxy urethane resins, epoxy phenol novolac resins (EPN) and epoxy cresol novolac resins (ECN).

[0069] The polyurethanes used according to the invention may exhibit crosslinking or, preferably, may not exhibit crosslinking. In the latter case, they are thermoplastic polyurethanes. The polyurethanes are preferably reaction products of organic polyhydroxylated compounds, polyether or polyester diols, and a diisocyanate. Preferred diisocyanates are aliphatic diisocyanates, such as isophorone diisocyanate, 4,4'-dicyclohexane diisocyanate, or mixtures thereof. Other suitable diisocyanates include, for example, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, 4,6-xylene diisocyanate, paraphenylene diisocyanate, cyclohexyl diisocyanate, 3,3'-tolidole-4,4'-diisocyanate, and 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate.

[0070] Polyurethane ionomers containing ionic side groups, such as sulfonate or carboxylate groups, are also suitable. They have the advantage of facilitating the formation of stable dispersions of the polyurethane in water.

[0071] The various polyurethane dispersions useful in the present invention include, among others, aqueous emulsions of blocked polyurethane resins, such as aqueous solutions of polyurethane polymers formed by a reaction between an organic isocyanate or polyisocyanate and an organic polyhydroxylated compound or a hydroxyl-terminated polyether or polyester polymer. The polyurethane dispersion may contain a crosslinking group. Other suitable examples are chain-extended thermoplastic polyurethanes derived from the chain extension of an isocyanate-terminated prepolymer prepared by the reaction of an aliphatic or cycloaliphatic diisocyanate with a polyalkylene ether polyol.

[0072] A suitable polyurethane crosslinker dispersion is an anionic aliphatic, low-branched polyester-based polyurethane emulsion containing caprolactam-blocked isocyanate, which promotes curing of the polyurethane polymer at a temperature greater than about 150°C. Specifically, a suitable polyurethane crosslinker dispersion comprises an aqueous dispersion of a high molecular weight branched polyurethane polymer based on polyester polyol or polyether polyol and 1,1-methylene-bis-(isocyanatocyclohexane), wherein a portion of the polymer chains are terminated with blocked isocyanate groups.

[0073] Other suitable polyurethane crosslinker dispersions include polyurethane / isocyanate emulsions of an aliphatic polyurethane containing blocked isocyanate. Other suitable polyurethane crosslinker dispersions include a polyurethane and a trimer of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate ("isophorone diisocyanate" or "IPDI") blocked with butanone oxime. Other blocking groups such as phenols, cresols, caprolactam, malonates, acetoacetates, and sodium bisulfite may also be used.

[0074] The sizing composition (b) used in the present invention may further contain a number of additives, as exemplified below. These additives may be contained alone or in any combination in addition to components (b1) to (b3) in (b):

[0075] • pH adjusters, such as bases, preferably ammonia or sodium hydroxide, and acids, preferably acetic acid or phosphoric acid;

[0076] • non-ionic lubricant, preferably a fatty alcohol or fatty acid monoester of polyethylene glycol (PEG), such as PEG 200 monolaurate, PEG 600 monooleate, PEG 600 monostearate, PEG 400 monostearate, PEG 400 monooleate, PEG 600 monolaurate;

[0077] • cationic lubricant, such as a polyethyleneimine polyamide salt;

[0078] • Antistatic agent such as a quaternary ammonium salt, tetraethylammonium chloride or lithium chloride;

[0079] • Antifoam agents such as polysiloxane derivatives;

[0080] • Isocyanate-based crosslinkers such as isocyanurate, biuret, carbodiimide;

[0081] • a boron-containing compound such as boric acid, boron oxide, sodium tetraborate, potassium metaborate, potassium tetraborate, ammonium biborate, ammonium tetrafluoroborate, butylammonium tetrafluoroborate, calcium tetrafluoroborate, lithium fluoroborate, potassium tetrafluoroborate, sodium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate and zinc tetrafluoroborate;

[0082] • a hypophosphite-containing compound or phosphite-containing compound, such as sodium hypophosphite, ammonium hypophosphite, calcium hypophosphite, trisnonylphenyl phosphite.

[0083] The impact modifier of component (C) is preferably selected from the following group: natural rubber, polybutadiene, polyisoprene, polyisobutylene, copolymer of butadiene and / or isoprene with styrene or styrene derivatives, hydrogenated such copolymer, copolymer produced by grafting or copolymerization with acid anhydrides, (meth)acrylic acid and its esters, graft rubber with a crosslinked elastomeric core consisting of butadiene, isoprene and / or alkyl acrylates and having a graft shell of polystyrene, olefin homo- and copolymers including ethylene-propylene, ethylene-butylene, ethylene-propylene-diene and ethylene-octene or ethylene-vinyl acetate rubber, non-polar or polar olefin- Homopolymers and copolymers obtained by grafting or copolymerization with acid anhydrides, (meth)acrylic acid and / or their esters,carboxylic acid-functionalized copolymer such as poly(ethene-co-(meth)acrylic acid) or poly(ethene-co-1-olefin-co-(meth)acrylic acid), wherein the 1-olefin can be an alkene or an unsaturated (meth)acrylic acid ester having more than 4 atoms, including those copolymers in which the acid groups are partially neutralized with metal ions, or a mixture thereof.

[0084] Examples of styrene-based block copolymers include styrene-(ethylene-butylene) diblock and styrene-(ethylene-butylene)-styrene triblock copolymers.

[0085] According to a further preferred embodiment, the molding compositions according to the invention are characterized in that component (C) contains a polyolefin homopolymer or an ethylene-α-olefin copolymer, particularly preferably an EP and / or EPDM elastomer (ethylene-propylene rubber or ethylene-propylene-diene rubber). For example, it can be an elastomer which is based on an ethylene-C3-12-α-olefin copolymer with 20 to 96, preferably 25 to 85 wt.% ethylene, wherein the C3-12-α-olefin is particularly preferably an olefin selected from the group propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene and / or 1-dodecene, and wherein component (C) is particularly preferably ethylene-propylene rubber and / or LLDPE and / or VLDPE.Alternatively or additionally (for example in a mixture), (C) can contain a terpolymer based on ethylene-C3-12-α-olefin with an unconjugated diene, which preferably contains 25 to 85% by weight of ethylene and up to a maximum of 10% by weight of an unconjugated diene, wherein the C3-12-α-olefin is particularly preferably an olefin selected from the group consisting of propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene and / or 1-dodecene, and / or wherein the unconjugated diene is preferably selected from the group consisting of bicyclo(2.2.1)heptadiene, 1.4-hexadiene, dicyclopentadiene and / or in particular 5-ethylidenenorbornene.

[0086] Ethylene-acrylate or ethylene-butylene-acrylate copolymers can also be used as components for component (C).

[0087] Preferably, component (C) comprises constituents having carboxylic acid or carboxylic acid anhydride groups which are introduced by thermal or radical reaction of the main chain polymer with an unsaturated dicarboxylic acid anhydride, an unsaturated dicarboxylic acid or an unsaturated dicarboxylic acid monoalkyl ester in a concentration sufficient for good bonding to the polyamide, reagents selected from the following group being preferably used for this purpose: maleic acid, maleic anhydride, maleic acid monobutyl ester, fumaric acid, aconitic acid and / or itaconic anhydride.

[0088] Preferably, 0.1 to 4.0 wt.% of an unsaturated anhydride is grafted onto the impact-resistant component as a component of (C), or the unsaturated dicarboxylic anhydride or its precursor is grafted together with another unsaturated monomer. In general, the degree of grafting is preferably in a range of 0.1-1.0%, particularly preferably in a range of 0.3-0.7%. Also possible as a component of component (C) is a mixture of an ethylene-propylene copolymer and an ethylene-butylene copolymer, this with a maleic anhydride grafting degree (MAH grafting degree) in the range of 0.3-0.7%. The possible systems for the component specified above can also be used in mixtures.

[0089] The SZM used as component (C) thus include homopolymers or copolymers of olefins, such as ethylene, propylene, butene-1, or copolymers of olefins and copolymerizable monomers, such as vinyl acetate, (meth)acrylic acid esters and methylhexadiene.

[0090] Examples of crystalline olefin polymers are low, medium and high density polyethylene, polypropylene, polybutadiene, poly-4-methylpentene, ethylene-propylene block or random copolymers, ethylene-methylhexadiene copolymers, propylene-methylhexadiene copolymers, ethylene-propylene-butene copolymers, ethylene-propylene-hexene copolymers, ethylene-propylene-methylhexadiene copolymers, poly(ethylene-vinyl acetate) (EVA), poly(ethylene-ethyl acrylate) (EEA), ethylene-octene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-propylene-diene terpolymers and combinations of the above polymers.

[0091] Examples of commercially available impact modifiers that can be used as part of component (C) are: TAFMER MC201: g-MAH (-0.6%) blend of 67% EP copolymer (20 mol% propylene) + 33% EB copolymer (15 mol% butene-1)); TAFMER MH5010: g-MAH (-0.6%) ethylene-butylene copolymer; TAFMER MH7010: g-MAH (0.7%) ethylene-butylene copolymer; Mitsui; TAFMER MH7020: g-MAH (0.7%) EP copolymer from Mitsui Chemicals; EXXELOR VA1801: g-MAH (0.7%) EP copolymer; EXXELOR VA1803: g-MAH (0.5-0.9%) EP copolymer, amorphous; EXXELOR VA1810: g-MAH (0.5%) EP copolymer; EXXELOR MDEX 94-1 1: g-MAH (0.7%) EPDM, Exxon Mobile Chemical; FUSABOND MN493D: g-MAH (0.5%) ethylene-octene copolymer; FUSABOND A EB560D (g-MAH) ethylene-n-butyl acrylate copolymer; ELVALOY, DuPont; Kraton FG1901GT: g-MAH (1.7%) SEBS with an S to EB ratio of 30:70; Lotader AX8840: ethylene-glycidyl methacrylate copolymer.

[0092] Also preferred is an ionomer in the context of component (C) in which the polymer-bound carboxyl groups are wholly or partially bonded to one another by metal ions.

[0093] Particularly preferred are copolymers of butadiene with styrene functionalized by grafting with maleic anhydride, non-polar or polar olefin homo- and copolymers formed by grafting with maleic anhydride and carboxylic acid functionalized copolymers such as poly(ethene-co-(meth)arylic acid) or poly(ethene-co-1-olefin-co-(meth)acrylic acid), in which the acid groups are partially neutralized with metal ions.

[0094] The additives of component (D) are preferably selected from the following group: polymers, in particular polyamides, different from component (A) and (C) and from (E), stabilizers, ageing inhibitors, antioxidants, antiozonants, light stabilizers, UV stabilizers, UV absorbers, UV blockers, inorganic heat stabilizers, in particular based on copper halides and alkali halides, organic heat stabilizers, conductivity additives, carbon black, optical brighteners, processing aids, nucleating agents, crystallization accelerators, crystallization retarders, flow aids, lubricants, mold release agents, plasticizers, pigments, dyes, marking substances, and mixtures thereof.

[0095] Polymers other than components (A) and (C) and (E) can be: polycarbonate, polystyrene, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, polyolefin, polyoxymethylene, polyester, in particular polyethylene terephthalate, polybutylene terephthalate, polysulfone (in particular of the PSU, PESU, PPSU type), polyphenylene ether, polyphenylene sulfide, polyphenylene oxide, liquid crystalline polymers, polyether ketone, polyether ether ketone, polyimide, aliphatic polyamides, polyamideimide, polyesterimide, polyether amide, polyester amide, polyether ester amide, polyurethane (in particular of the TPU, PUR type), polysiloxane, polyacrylate, polymethacrylate and mixtures or copolymers based on such systems.

[0096] The additives of component (D) preferably contain polyamides different from component (A) and (C) and (E), particularly preferably purely aliphatic polyamides selected from the group: PA6, PA66, PA 10, PA 11, PA12, PA 516, PA 610, PA 612, PA 614, PA 616, PA 618, PA 1010, PA 1012, PA 1014, PA 1016, PA 1018 and mixtures thereof, with PA 10, PA 11, PA 12, PA 516, PA 612, PA 616, PA 1010, PA 1012, PA 1016, PA 1212 and mixtures thereof being preferred.

[0097] The amorphous, partially aromatic polyamide of component (E) is preferably selected as an amorphous, partially aromatic copolyamide, in particular as a copolyamide 6I / 6T, preferably with a 6T content in the range of 20 to 45 mol%.

[0098] Compared to semi-crystalline polyamides, amorphous polyamides exhibit no or only a very low, barely detectable heat of fusion. In differential scanning calorimetry (DSC) according to ISO 11357 (2013) at a heating rate of 20 K / min, amorphous polyamides preferably exhibit a heat of fusion of less than 5 J / g, more preferably a maximum of 3 J / g, and most preferably between 0 and 1 J / g. Due to their amorphous nature, amorphous polyamides do not have a melting point.

[0099] A "flowmeter" test specimen made from the polyamide molding compound preferably has a bursting pressure measured according to the protocol described above of at least 70 MPa, preferably of at least 90 MPa, and particularly preferably of at least 100 MPa.

[0100] A standard specimen "tensile bar with frontal weld line" made from the polyamide molding compound preferably has a breaking stress of at least 90 MPa in the presence of a weld line without exposure to chemicals.

[0101] The ultimate stress is understood as the strength of the weld line, measured as specified further below in the description. A test specimen made from the polyamide molding compound, a "tensile test piece with a frontal weld line" (weld line tensile test piece), preferably after storage in a mixture of ethylene glycol and water at 130 °C for at least 500 hours, has a ultimate stress of at least 50 MPa, preferably at least 60 MPa.

[0102] A test specimen "tensile test piece with frontal weld line" (weld line tensile test piece) produced from the polyamide molding compound preferably has a breaking stress of at least 25 MPa, preferably of at least 40 MPa, particularly preferably of at least 50 MPa after storage in a mixture of ethylene glycol and water at 130 °C for at least 1000 hours.

[0103] The present invention further relates to a molded article which contains such a polyamide molding compound and which preferably consists of this polyamide molding compound.

[0104] The present invention further relates to a process for producing such a shaped body, characterized in that such a polyamide molding compound is melted and formed into the shaped body in an injection molding process, wherein preferably at least one weld line is formed.

[0105] Last but not least, the present invention relates to a process for producing such a polyamide molding compound, characterized in that components (A) and (B) and optionally (C) and / or (D) are melted and mixed, preferably in an extruder, optionally followed by subjecting the mixture to a melt post-condensation process at a temperature between 320 and 360 °C.

[0106] Further embodiments are specified in the dependent claims.

[0107] BRIEF DESCRIPTION OF THE DRAWINGS

[0108] Preferred embodiments of the invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. In the drawings:

[0109] Fig. 1 shows the test specimen (flowmeter) used to measure the bursting pressure, with a) a first perspective view and b) a second perspective view with the weld lines A and B.

[0110] DESCRIPTION OF PREFERRED EMBODIMENTS

[0111] The following examples are intended to illustrate the subject matter of the invention in more detail, without intending to limit it to the specific embodiments shown here.

[0112] The materials used in the examples and comparative examples are as follows: Component A:

[0113] Polyamide type A: Semi-crystalline, semi-aromatic polyamide PA 6T / 6I made from 1,6-hexanediamine, terephthalic acid (70 mol%) and isophthalic acid (30 mol%) with a melting point of 325°C and a relative viscosity of 1.67;

[0114] Polyamide type A1: Semi-crystalline, semi-aromatic polyamide PA 6T / 6I / 6 made from 1,6-hexanediamine, terephthalic acid (72 mol%), isophthalic acid (18 mol%) and caprolactam (10 mol%) with a melting point of 304°C and a relative viscosity of 1.63.

[0115] Component E:

[0116] Polyamide type B: Amorphous, semi-aromatic polyamide PA 6I / 6T made from 1,6-hexanediamine, terephthalic acid (33 mol-%) and isophthalic acid (67 mol-%) with a glass transition temperature of 125 °C and a relative viscosity of 1.57;

[0117] Component B:

[0118] Glass fiber type 1A: Nittobo CS3DE-256, average diameter 6 pm, length 3 mm, glass fiber sizing contains aminopropyltriethoxysilane and a polyurethane resin, but no component of type b2 (not according to the invention);

[0119] Glass fiber type 1Ba: CPIC 301HP-DE, average diameter 6 pm, length 3 mm, glass fiber sizing contains aminopropyltriethoxysilane (b1) and polyacrylic acid (b2) and a polyurethane resin (b3).

[0120] Glass fiber type 1Bb: NEG 289-DE, average diameter 6 pm, length 3 mm, glass fiber sizing contains aminopropyltriethoxysilane (b1) and polyacrylic acid (b2) and a polyurethane resin (b3).

[0121] Glass fiber type 1Bc: Nittobo CSG3-810DE, average diameter 6 pm, length 3 mm, glass fiber sizing contains aminopropyltriethoxysilane (b1) and polyacrylic acid (b2) and a polyurethane resin (b3).

[0122] Glass fiber type 2A: Vetrotex 995 EC10-4.5, average diameter 10 pm, length 4.5 mm,

[0123] Glass fiber sizing contains aminopropyltriethoxysilane and a polyurethane resin (not according to the invention);

[0124] Glass fiber type 2B: CPIC 301 HP, average diameter 10 pm, length 3 mm, glass fiber sizing contains aminopropyltriethoxysilane (b1) and polyacrylic acid (b2) and a polyurethane resin (b3) (not according to the invention);

[0125] Component C:

[0126] SZM-1: Impact modifier, blend of ethylene / propylene copolymer and

[0127] Ethylene / 1-butene copolymer in a weight ratio of 67:33, 0.6 wt.% maleic anhydride, Tafmer MC201 (Mitsui Chemicals, Japan),

[0128] SZM-2: Impact modifier, ethylene glycidyl methacrylate copolymer

[0129] (Copolymer of 92% ethylene and 8% glycidyl methacrylate)), Lotader AX8840 (Arkema, France)

[0130] SZM-3: Impact modifier, ethylene methacrylic acid acrylate terpolymer, partially neutralized with zinc ions, Surlyn 9320 (DuPont).

[0131] Component D:

[0132] Stabilizer: Mixture of Hostanox PAR24 (based on tris-(2,4-ditertiarybutylphenyl) phosphite) and Irganox 1098 (N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide]) in a weight ratio of 1:1.

[0133] Color masterbatch: MB PA66 / Black Pearls 4750 (75 / 25% by weight)

[0134] Examples and comparison examples

[0135] Production of PA molding compounds

[0136] To produce the polyamide molding compounds of the invention, components (A) and (B) and optionally (C) and (D) are mixed on conventional compounding machines, such as single- or twin-screw extruders or screw mixers. The components are fed individually or in the form of a dry blend into the feed via gravimetric metering scales, or separately via the feed and a side feeder. Component (B) is preferably metered into the polymer melt via a side feeder.

[0137] If additives (components C and D) are used, they can be added directly or in the form of a masterbatch. The carrier material of the masterbatch is preferably a polyamide or a polyolefin. Among the polyamides, the polyamide of component (A), PA66, PA610, PA 11, PA 12, PA 612, PA 1010, or PA 1212, is particularly suitable.

[0138] The components listed in Table 2 were compounded in a twin-screw extruder from Werner and Pfleiderer with a screw diameter of 25 mm under specified process parameters (Table 1A). The polyamide granules and additives were metered into the feed zone, while the glass fiber was metered into the polymer melt via a side feeder three housing units upstream of the die. The compounds were drawn as strands from a 2.5 mm diameter die and, after water cooling, pelletized. The pellets were dried for 24 hours at 110°C under a vacuum of 30 mbar. Table 1A: Process parameters for compounding

[0139] Table 1B: Process parameters for injection molding flowmeter

[0140] Table 1C: Process parameters for injection molding weld line tensile bar

[0141] Production of the test specimens

[0142] The test specimens (tensile bars and tensile bars with a frontal weld line, also called weld line tensile bars) were manufactured on an Arburg Allrounder 320-210-750 injection molding machine under specified process parameters (Table 1C), with barrel temperatures set between 330°C and 365°C and a screw peripheral speed of 16 m / min. The mold temperature was set to 170°C.

[0143] The flowmeter test specimens were manufactured on an ENGEL e-victory 120 injection molding machine with a hot runner, with barrel temperatures set between 320°C and 340°C and a screw speed of 120 rpm. The process parameters for injection molding the flowmeters are summarized in Table 1B.

[0144] The "flowmeter" test specimen used for measuring burst pressure is 130 mm long, has an inner diameter of the main pipe 2 of 21 mm, an inner diameter of the nozzle 3 of 11 mm, a wall thickness in the main pipe area of ​​3 mm, and a wall thickness in the nozzle area of ​​1.7 mm, with weld lines A and B (arrows in b) and is shown schematically in Fig. 1. A G1" thread is formed at each of the opposite ends of the main pipe 2, and a G3 / 8" thread is formed at nozzle 3. Weld line A is generally the first weld line to yield, and the first weld line to yield must be considered for the weld line strength value (measured as burst pressure).

[0145] Measurement methods

[0146] Tensile modulus of elasticity: ISO 527 with a tensile speed of 1 mm / min, ISO tensile test specimen (manufactured using injection points opposite each other at the ends of the test specimen so that the inflowing molding compound flowed from the outside into the center of the mold cavity and a weld line formed in the center of the molded body), standard: ISO / CD 3167, type A1, 170 x 20 / 10 x 4 mm, temperature 23 °C.

[0147] Tensile stress, elongation, and fracture energy: ISO 527 at a tensile speed of 5 mm / min. ISO tensile test specimen. Standard: ISO / CD 3167, Type A1, 170 x 20 / 10 x 4 mm, temperature 23°C.

[0148] The ISO tensile test specimen was manufactured using injection points located opposite each other at the ends of the test specimen, so that the inflowing molding compound flowed from the outside into the center of the mold cavity and a weld line formed in the center of the molded body.

[0149] Relative viscosity: DIN EN ISO 307, in 0.5 wt.% m-cresol solution, temperature 20 °C.

[0150] Melting point (T m ) and enthalpy of fusion (AH m ): The melting point was determined according to ISO 11357-3 (2018) on granules. Differential scanning calorimetry (DSC) was performed at a heating rate of 20 K / min. After the first heating, the sample was quenched in dry ice. The melting point was determined during the second heating. The temperature at the peak maximum was given as the melting point.

[0151] Burst pressure: The flowmeter, with the free nozzles closed, is filled with water, mounted in a burst pressure test rig using a hydraulic quick coupling, and subjected to a burst pressure test (short-term internal pressure loading until failure) at 23°C with a pressure increase of 2 bar / s. The maximum pressure reached (average over 5 samples) is given in the tables.

[0152] Hydrolytic stability to coolant: Hydrolytic stability is determined according to the GM standard GMW15468 (2011). For this purpose, test specimens (ISO tensile test specimens), dry as they occur in injection molding, are stored in a glycol-water mixture (1:1) in a pressure vessel at 130°C for 504 hours. The glycol used is VW coolant additive G13 according to the VW TL 774 J standard. After storage, the test specimens are cooled to 23°C in the coolant, removed from the coolant, rinsed with water, wiped with a cotton cloth, and stored in a desiccator over silica gel. Within 7 days of sampling, the previously described tensile test according to ISO 527 is performed on the stored test specimens.

[0153] Results

[0154] Tables 2 and 3 document the compositions of the polyamide molding compounds according to the invention and comparative examples, as well as the measurements taken therein. Table 2: Composition and burst pressure flowmeter for the inventive polyamide molding compounds B1 and B7 as well as the

[0155] Comparative tests VB1 to VB5

[0156] It turns out that the bursting pressure when using 6-micrometer-thin glass fibers with the inventive sizing is significantly higher immediately after injection molding, namely significantly above 70, above 80, or even above 90 or 100 bar. The strength of the weld line, documented here as breaking stress, is also slightly higher at the beginning (before storage) with the inventive 6-micrometer-thin glass fibers than with glass fibers with a 10-micrometer cross-section.

[0157] Table 3: Composition and properties of the weld line tensile test piece before and after storage for the inventive

[0158] Polyamide molding compounds B1-B7 and the comparative tests VB1 to VB5

[0159] The special and unexpected advantages of the inventive molding compound containing inventive glass fibers with a polyacrylic acid-containing sizing agent become apparent when the component is exposed to chemicals for a prolonged period and at elevated temperatures, in this case, in particular to a mixture of equal parts ethylene glycol and water at 130°C. While in Comparative Examples 1 and 2, the weld line strength is halved after just 500 hours, Examples B1 and B3 show a much smaller reduction in weld line strength. The additional use of component (E) in Examples B6 and B7 achieves a further increase in the fracture stress (weld line strength on the tensile test specimen) both before and after storage in a glycol-water mixture at 130°C.A comparison with VB5 clearly shows that this improvement can only be achieved by using the inventive glass fiber. The type 2A glass fiber delivers significantly lower breaking stress before and after storage in glycol / water. The elongation at break is also significantly more stable when using the inventive polyamide molding compound with inventive glass fibers with a polyacrylic acid-containing size. The same applies to the fracture energy when using the inventive polyamide molding compound.

[0160] In the following Table 4, further examples BB1-BB6 according to the invention as well as a further comparative example VBB1 are documented using further types of impact modifiers.

[0161] Table 4: Composition and properties of the weld line tensile test before and after storage for the inventive polyamide molding compounds BB1 to BB6 and the comparative test VBB1

[0162] In the following Table 5, further examples BB8-BB9 according to the invention as well as a further comparative example VBB2 are documented using further types of polyamides of component A.

[0163] Table 5: Composition and properties of the weld line tensile test before and after storage for the inventive polyamide molding compounds BB7 and BB8 and the comparative test VBB2 The special and unexpected advantages of the inventive molding compound with glass fibers and polyacrylic acid-containing sizing are also evident here, especially when the component is exposed to chemicals for a prolonged period and at elevated temperatures, in this case in particular to a mixture of equal parts of ethylene glycol and water at 130 °C. The elongation at break is also essential when using the inventive polyamide molding compound with glass fibers and polyacrylic acid-containing sizing, and the same applies to the fracture energy when using the inventive polyamide molding compound.

[0164] Storage in water at 95 °C according to Table 4 shows that there is hardly any reduction in weld line strength (breaking stress, since the fracture occurs in the weld line) for the inventive examples BB1 to BB6. Furthermore, examples BB1 to BB6 demonstrate that good weld line strengths can be achieved through the use of various impact modifiers. When stored in water at 125 °C according to Table 5, the weld line strength of examples BB7 and BB8 remains at a high level and decreases only slightly compared to the initial values. Comparative example VBB2 already starts at a significantly lower level of weld line strength, and storage in water at 125 °C reduces this value significantly more than for BB7 and BB8.

[0165] LIST OF REFERENCE SYMBOLS

[0166] 1 test specimen "Flowmeter" for A, B weld line burst pressure measurements GF glass fiber

[0167] 2 main pipe SZM impact modifier,

[0168] 3 nozzle impact modifier

[0169] 4 sprue

Claims

PATENT CLAIMS 1. Thermoplastic polyamide molding compound consisting of the following components: (A) 30 to 74.5 wt.% of at least one semi-crystalline, semi-aromatic Copolyamide 6T / Z with a melting point of at least 270 °C, wherein the polyamide unit Z is composed of at least one lactam or one aminocarboxylic acid and / or of polyamide units different from 6T composed of at least one diamine and at least one dicarboxylic acid, wherein in 6T / Z the 6T proportion is more than 50 mol%, based on the molar proportions of all polyamide units; (B) 25 to 50 wt.% glass fibers having an average diameter of 5 to 8 pm, wherein the glass fibers are coated with a sizing composition (b) containing (b1) at least one silane compound (b2) at least one polymer or copolymer based on unsaturated carboxylic acids and / or unsaturated carboxylic anhydrides, and (b3) at least one epoxy, polyurethane or polyamide resin, with the proviso that if component (b1) or component (b3) is a system containing carboxylic acid and / or anhydride, the sizing composition may also not contain component (b2); (C) 0.5 to 8 wt% impact modifier; (E) 0 to 20 wt.% amorphous, semi-aromatic polyamide; (D) 0 to 10 wt.% of additives other than (A) - (C) and (E); and wherein the sum of components (A) to (E) amounts to 100 wt.% of the polyamide molding composition.

2. Polyamide molding composition according to claim 1, characterized in that the Z of component (A) is constructed from polyamide units of at least one lactam or aminocarboxylic acid having at least four, preferably 5-12 carbon atoms, wherein preferably lactam and / or aminocarboxylic acid are selected as aliphatic linear systems, and / or Z is constructed from polyamide units other than 6T of at least one diamine having 5-12 carbon atoms and at least one dicarboxylic acid having 5-12 carbon atoms, preferably diamines are selected as aliphatic linear or cyclic diamines and further preferably dicarboxylic acids are selected as aliphatic linear dicarboxylic acids.

3. Polyamide molding compound according to one of the preceding claims, characterized in that the copolyamide of the structure 6T / Z is selected from the group 6T / 6I, 6T / DT, 6T / BACT, 6T / 66, 6T / 610, 6T / 612, 6T / 6I / 6, 6T / 6I / 66, 6T / 6I / 610, 6T / 6I / 612, or a mixture thereof, wherein preferably the proportion of polyamide units other than 6T, in particular 6I, DT, 66, 610, 612 or BACT proportion is more than 20 mol-% and wherein the said copolyamides optionally also contain further polyamide units XY selected from the group consisting of 56, 66, 610, 612, BACI, BAC6, BAC10 and BAC12 in a proportion of less than 30 mol-%.

4. Polyamide molding compound according to one of the preceding claims, characterized in that the copolyamide 6T / Z is selected as 6T / 6I with a proportion of 6T polyamide units of 60-80 mol%, preferably in the range of 65-75 mol%.

5. Polyamide molding compound according to one of the preceding claims, characterized in that the proportion of component (A) is in the range of 37-74.5% by weight or 42-70% by weight, preferably in the range of 48-64.4% by weight; and / or that the proportion of component (B) is in the range of 30-45% by weight, preferably in the range of 35-42% by weight; and / or that the proportion of component (C) is in the range of 0.5-6% by weight or 0.5-5% by weight, preferably in the range of 0.7-5.0% by weight or 0.7-3.5% by weight; and / or that the proportion of component (E) is in the range of 5-20% by weight, preferably in the range of 6-16% by weight; and / or that the proportion of component (D) is in the range of 0-7 percent by weight, preferably in the range of 0.1-5.0 percent by weight, the sum of components (A)-(E) adding up to 100 percent by weight of the polyamide molding compound.

6. Polyamide molding compound according to one of the preceding claims, characterized in that the sizing composition (b) contains as component (b1) as silane compound an aminosilane, preferably an aminoalkyltrialkoxysilane, preferably an aminoalkyltriethoxysilane, particularly preferably at least one aminopropyltriethoxysilane or aminopropyltriethoxysilane, and / or as component (b2) at least one polyacrylic acid or an olefin-maleic anhydride copolymer, and / or as component (b3) a polyurethane resin, wherein preferably the sizing composition contains the three components (b1)-(b3) as a mixture or multi-layer coating, preferably as a mixture of aminopropyltriethoxysilane, polyacrylic acid or olefin-maleic anhydride copolymer and polyurethane resin.

7. Polyamide molding compound according to one of the preceding claims, characterized in that the impact modifier of component (C) is selected from the following group: natural rubber, polybutadiene, polyisoprene, polyisobutylene, copolymer of butadiene and / or isoprene with styrene or styrene derivatives, hydrogenated copolymer of this type, copolymer produced by grafting or copolymerization with acid anhydrides, (meth)acrylic acid and its esters, graft rubber with a crosslinked elastomeric core consisting of butadiene, isoprene and / or alkyl acrylates and having a graft shell of polystyrene, olefin homo- and copolymers including ethylene-propylene, ethylene-butylene, ethylene-propylene-diene and ethylene-octene or Ethylene vinyl acetate rubber, non-polar or polar olefin homopolymer and copolymer obtained by grafting or copolymerizing with acid anhydrides, (meth)acrylic acid and / or their esters,carboxylic acid-functionalized copolymer such as poly(ethene-co-(meth)acrylic acid) or poly(ethene-1-olefin-co-(meth)acrylic acid), wherein the 1-olefin can be an alkene or an unsaturated (meth)acrylic acid ester having more than 4 atoms, including those copolymers in which the acid groups are partially neutralized with metal ions, or a mixture thereof.

8. Polyamide moulding compound according to one of the preceding claims, characterized in that the additives of component (D) are selected from the following group: polymers, in particular polyamides, different from components (A) and (C) and (E), stabilizers, age inhibitors, antioxidants, antiozonants, Light stabilizers, UV stabilizers, UV absorbers, UV blockers, inorganic heat stabilizers, in particular based on copper halides and alkali halides, organic heat stabilizers, conductivity additives, carbon black, optical brighteners, processing aids, nucleating agents, crystallization accelerators, crystallization retarders, flow aids, lubricants, mold release agents, plasticizers, pigments, dyes, marking agents, and mixtures thereof and / or that component (E) is selected as an amorphous, partially aromatic copolyamide, in particular as a copolyamide 6I / 6T, preferably with a 6T content in the range from 20 to 45 mol%.

9. Polyamide molding compound according to one of the preceding claims, characterized in that the additives of component (D) contain polyamides different from components (A) and (E), particularly preferably purely aliphatic polyamides selected from the group: PA 10, PA 11, PA12, PA 516, PA 6, PA 66, PA 610, PA 612, PA 614, PA 616, PA 618, PA 1010, PA 1012, PA 1014, PA 1016, PA 1018 and mixtures thereof, with PA 10, PA 11, PA 12, PA 516, PA 612, PA 616, PA 1010, PA 1012, PA 1016, PA 1212 and mixtures thereof being preferred.

10. Polyamide molding compound according to one of the preceding claims, characterized in that a flowmeter test specimen produced from the polyamide molding compound has a bursting pressure according to the description of at least 70 MPa, preferably of at least 90 MPa and particularly preferably of at least 100 MPa; and / or that a standard specimen produced from the polyamide molding compound without chemical exposure in the presence of a weld line has a breaking stress of at least 90 MPa, and / or after storage in a mixture of ethylene glycol and water (1:1) at 130 °C for at least 500 hours has a breaking stress of at least 50 MPa, preferably of at least 60 MPa.

11. A molded body which contains a polyamide molding compound according to one of claims 1 to 10 and which preferably consists of this polyamide molding compound.

12. A process for producing a shaped body according to claim 11, characterized in that a polyamide molding compound according to any one of claims 1-10 is melted and molded into the shaped body in an injection molding process, wherein at least one weld line is formed.

13. A process for producing a polyamide molding composition according to any one of claims 1-10, characterized in that components (A) and (B) and optionally (C) and / or (D) and / or (E) are melted and mixed, preferably in an extruder, followed by subjecting the mixture to a melt post-condensation process at a temperature between 320 and 360 °C.

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